Android Content Provider(内容提供者)
一、简介
定义内容提供者可以开发自己已用的数据操作给第三方调用,下面的示例中用到了Android test case ,主要是为了给数据库中添加数据方便内容提供者读取。
二、Test case 添加DB数据
1、声明单元测试
<instrumentation android:name="android.test.InstrumentationTestRunner" android:targetPackage="com.am.cpv" /> <application android:allowBackup="true" android:icon="@drawable/ic_launcher" android:label="@string/app_name" android:theme="@style/AppTheme" > <uses-library android:name="android.test.runner" /> </application>2、创建数据库工具类SQLiteOpenHelper
import android.content.Context; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteOpenHelper; public class MyDBOpenHelper extends SQLiteOpenHelper { public MyDBOpenHelper(Context context) { super(context, "person.db", null, 1); } @Override public void onCreate(SQLiteDatabase db) { db.execSQL("create table person (id integer primary key autoincrement,name varchar(20),number varchar(20))"); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { // TODO Auto-generated method stub } }3、创建AndroidTestCase,添加数据到数据库
import android.content.ContentValues; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase; import android.test.AndroidTestCase; import com.am.cpv.db.MyDBOpenHelper; public class AddDataTestCase extends AndroidTestCase { public void testAdd() { MyDBOpenHelper oh = new MyDBOpenHelper(getContext()); SQLiteDatabase wdb = oh.getWritableDatabase(); // wdb.execSQL("insert into person(name) values(?)", new Object[]{"张三"}); for (int i = 0; i < 30; i++) { ContentValues values = new ContentValues(); values.put("name", "name" + i); values.put("number", "110-" + i); wdb.insert("person", null, values); } wdb.close(); } public void testQuery() { MyDBOpenHelper oh = new MyDBOpenHelper(getContext()); SQLiteDatabase wdb = oh.getWritableDatabase(); // Cursor cursor = wdb.rawQuery("select * from person ", new String[] {}); Cursor cursor2 = wdb.query("person", null, null, new String[] {}, null, null, null); while (cursor2.moveToNext()) { String[] columnNames = cursor2.getColumnNames(); for (String colName : columnNames) { int columnIndex = cursor2.getColumnIndex(colName); String val = cursor2.getString(columnIndex); System.out.print(val + " "); } System.out.println(); } } }
三、创建内容提供者
1、创建ContentProvider
import android.content.ContentProvider;
import android.content.ContentValues;
import android.content.UriMatcher;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.net.Uri;
import com.am.cpv.db.MyDBOpenHelper;
public class PersonProvider extends ContentProvider {
private static UriMatcher uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
private MyDBOpenHelper helper;
private static final int QUERY = 1;
static {
uriMatcher.addURI("com.am.persionProvider", "query", QUERY);
}
@Override
public boolean onCreate() {
helper = new MyDBOpenHelper(getContext());
return false;
}
@Override
public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
// 判断uri的请求是否为查询
if (uriMatcher.match(uri) == QUERY) {
SQLiteDatabase db = helper.getReadableDatabase();
Cursor cursor = db.query("person", projection, selection, selectionArgs, null, null, sortOrder);
return cursor;
} else {
return null;
}
}
//下边的代码未作实现
@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
// TODO Auto-generated method stub
return 0;
}
@Override
public String getType(Uri uri) {
// TODO Auto-generated method stub
return null;
}
@Override
public Uri insert(Uri uri, ContentValues values) {
// TODO Auto-generated method stub
return null;
}
@Override
public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
// TODO Auto-generated method stub
return 0;
}
}
2、AndroidManifest.xml中声明内容提供者
<provider android:name="com.am.cpv.pv.PersonProvider" android:authorities="com.am.persionProvider" android:exported="true" > </provider>
四、读取内容提供者的数据
public void click(View v) { ContentResolver cr = getContentResolver(); Uri uri = Uri.parse("content://com.am.persionProvider/query"); Cursor cursor = cr.query(uri, null, "name=?", new String[] { "name1" }, null); while (cursor.moveToNext()) { String[] columnNames = cursor.getColumnNames(); for (String colName : columnNames) { int columnIndex = cursor.getColumnIndex(colName); String val = cursor.getString(columnIndex); System.out.print(val + " "); } } }
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